How to Measure Yourself for Underwear — in Centimetres, Not Cup Letters

A 34B in one country is a 75B in another and neither tells you whether the thing will actually fit. If you are buying online, measurements in centimetres are the only reliable input.

What you need

A soft tape measure. If you do not own one, use a piece of string and hold it against a ruler afterwards — that is genuinely accurate enough. Measure against bare skin or a thin, unpadded bra, standing relaxed and breathing normally.

The most common mistake is pulling the tape tight. It should sit flat against you, snug but not compressing.

The three measurements

1. Underbust

Directly under the bust, where a band would sit. Keep the tape level all the way round — a tape that rides up at the back gives a number several centimetres too small. Exhale normally and read it.

This is the number that decides whether a bralette holds or slides.

2. Bust

Around the fullest part, usually across the nipple line. Stand straight, arms relaxed at your sides. Keep the tape level and do not pull.

The difference between bust and underbust is what cup letters are derived from — but with a wire-free bralette, that difference matters far less than the underbust does.

3. Hips

Around the widest part of the hips and seat, usually 18–20 cm below the natural waist. Feet together, tape level.

For briefs this is the number that matters, not your waist.

What to do when you are between sizes

• For briefs — size up. Underwear that is slightly loose is forgettable; underwear that is slightly tight leaves marks and rides up.
• For a bralette you will sleep in — size up. You want it to hold, not to grip.
• For a bralette you want more shape from — size down, but only if you are near the bottom of the range.
• If your bust and hips fall in different sizes, which is extremely common, buy each piece to its own measurement rather than forcing one size on both.

How to check the fit once it arrives

• Two fingers under the band. If you cannot fit them, it is too tight. If it slides down, it is too loose.
• Look for marks after an hour, not after a minute. A red line means the band is too narrow or too small.
• Sit down and move. Most bad fits only reveal themselves seated.
• For briefs, walk up stairs. If they ride, the cut is wrong for you, not the size.

Our sizing

We size S to L from these measurements rather than from cup letters, and the full chart in centimetres is on the size page. If you would rather not decide alone, send your three numbers on WhatsApp — one of us will read them and tell you which size we would send, including when the honest answer is that we do not have your size yet.

If you are new to wire-free, this guide to what you gain and give up is worth reading before you order.